Phosphor and manufacturing method for the same, and light source

ABSTRACT

To provide a phosphor having an emission spectrum with a broad peak in a range from yellow color to red color (580 nm to 680 nm) and an excellent excitation band on the longer wavelength side from near ultraviolet/ultraviolet of excitation light to visible light (250 nm to 550 nm), and having an improved emission intensity. The phosphor is provided, which is given by a general composition formula expressed by MmAaBbOoNn:Z, (wherein element M is more than one kind of element having bivalent valency, element A is more than one kind of element having tervalent valency selected from the group consisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb, and Bi, element B is more than one kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is more than one kind of element selected from rare earth elements or transitional metal elements, satisfying m&gt;0, a&gt;0, b&gt;0 o≧0, and n=2/3m+a+4/3b−2/3o), and further containing boron and/or fluorine.

TECHNICAL FIELD

The present invention relates to a phosphor used in a display such as acathode-ray tube (CRT), a field emission display (FED), and a plasmadisplay (PDP), and an illumination device such as a fluorescent lamp anda fluorescent display tube, and a backing light source for liquidcrystal display, and a method of manufacturing therefore, and also tothe light source using the phosphor.

BACKGROUND ART

At present, a white LED illumination has been focused as theillumination of the next generation. Conventionally, a discharge typefluorescent lamp and an incandescent bulb used as an illumination deviceinvolve problems that a harmful substance such as mercury is contained,life span is short, and heat generation is violent. However, in recentyears, a high luminance LED emitting light in a region of blue color andnear ultraviolet/ultraviolet, which is required for the white LEDillumination, has been developed sequentially. Also, study anddevelopment have been actively performed on using the white LEDillumination as the illumination of the next generation.

At present, two systems of the white LED illumination are proposed. Asone of them, a multi chip type system is given, in which three primarycolors of high luminance red LED, a high luminance blue LED, a highluminance green LED, are used. As the other of them, one chip system,which has been developed in recent years, is given, in which LED such asa high luminance ultraviolet LED and a high luminance blue LED, and thephosphor excited by the light having an emission spectrum with a peak inthe range from ultraviolet to blue color generated from the LED arecombined.

When the aforementioned two systems are compared, the one chip typesystem has a preferable characteristic as the light source forillumination, such that since it is constituted by combining an LED andthe phosphor, it can be small-sized, and the light guide for mixing theemission is simplified, and in addition, the drive voltage, the opticaloutput, and the temperature characteristic of each LED are not requiredto be taken into consideration, thus realizing cost reduction. Further,by using the phosphor having a broad emission spectrum, the whiteemission spectrum is approximated the spectrum of the sun-light, and thecolor rendering properties are possibly improved. This contributes tofocusing on the one chip type system as the illumination of the nextgeneration, compared with the multi chip type system.

Further two systems are generally considered for the one chip-type whiteLED illumination in which the high luminance LED and the phosphor arecombined. In one of them, the blue LED with high luminance and thephosphor emitting yellow color by being excited by blue light generatedfrom the LED are combined, and white color is obtained by using acomplementary relation between the blue emission of the LED and yellowemission of the phosphor. In the other of them, the LED emitting nearultraviolet/ultraviolet light, the phosphor emitting red (R) color, thephosphor emitting green (G) color, and the phosphor emitting blue (B)color by being excited by the near ultraviolet/ultraviolet lightgenerated from the LED are combined, and the white light is obtained bymixing the colors of the lights obtained from the phosphors of R, G, Band other phosphor.

As the white LED illumination combining the high luminance blue LED andthe phosphor emitting yellow color excited by the blue light generatedfrom the LED, the white LED combining the high luminance blue LED and ayellow phosphor (Y, Gd)₃(Al, Ga)₅O₁₂:Ce (expressed as YAG:Ce) isproposed. Such a white LED has an advantage that by using thecomplementary relation between the blue light and the yellow light, thekind of the phosphor to be used may be reduced, compared to the systemin which near ultraviolet/ultraviolet LED is used. Further, the yellowphosphor YAG:Ce to be used has an excitation spectrum with a peak nearthe wavelength of 460 nm of emission from the blue LED, thereby emittinglight with high efficiency, and the white LED of high luminance canthereby be obtained.

In the latter one chip-type white LED, white color is obtained by mixingthe colors of the emission from the phosphors such as R, G, B and soforth, by combining the LED emitting the near ultraviolet/ultravioletlight, the each phosphor emitting red (R), green (G), blue (B) colorsexcited by the near ultraviolet/ultraviolet light generated from theLED. A method of obtaining the white emission by mixing the emissionsuch as the R, G, B is characterized in that an arbitrary emission colorin addition to the white light can be obtained by controlling acombination and a mixing ratio of the R, G, B and also the whiteemission with excellent color rendering properties is obtained by therelation in a mixed state of colors not using the complementary relationbut using the R, G, B. Then, as the phosphor used for such anapplication, examples are given such as Y₂O₂S:Eu, La₂O₂S:Eu,3.5MgO.0.5MgF₂.GeO₂:Mn, (La, Mn, Sm)₂O₂S.Ga₂O₃:E , for the red phosphor,ZnS:Cu,Al, SrAl₂O₄:Eu, BAM:Eu,Mn, Ba₂SiO₄:Eu for the green phosphor, andBAM:Eu, Sr₅(PO₄)₃Cl:Eu, ZnS:Ag, (Sr, Ca, Ba, Mg)₁₀(PO₄)₆Cl₂:Eu for theblue phosphor.

However, in the former white LED illumination formed by combining thehigh luminance blue LED and the yellow phosphor (YAG:Ce), the lightemission in the longer wavelength side of a visible light region isinsufficient, resulting in a bluish white light emission. Then, a redemission spectrum in the vicinity of the wavelength range from 600 nm to700 nm is insufficient, thereby making it impossible to obtain aslightly reddish white light emission like a lamp bulb, to pose aproblem of deteriorated color rendering properties. Further, in regardsto an excitation range of the yellow phosphor YAG:Ce, although having anexcitation band with highest efficiency in the vicinity of 460 nmwavelength, the yellow phosphor YAG:Ce does not have the excitation bandwith excellent efficiency in a broad range. Therefore, by the variationin emission wavelength due to the variation in the light emittingelement during manufacturing the blue LED, the emission wavelength ofthe blue LED is deviated from an optimal excitation range of theYAG:Ce-based yellow phosphor, resulting in a situation of losing awavelength balance of blue color and yellow color. When such a situationoccurs, there is the problem that the color tone of the white lightobtained by synthesizing the blue light and the yellow light is changed.

In addition, In the latter white LED illumination formed by combiningthe near ultraviolet/ultraviolet LED and phosphors of R, G, B and soforth, an excitation efficiency and an emission efficiency of the redphosphor and so forth is lower compared with the phosphor of othercolors in an excitation range of the near ultraviolet/ultravioletregion. Therefore, the combination of the R, G, B and so forth has noother choice but increase the mixing ratio of only the red phosphor.This causes an insufficient mixing ratio of the phosphor such as thegreen phosphor improving the luminance, and the white color with highluminance can not be obtained. Further, the red phosphor according tothe conventional technique has a sharp emission spectrum, therebyinvolving the problem that the color rendering properties of the whitelight obtained is unsatisfactory.

In order to solve the aforementioned problem, it is necessary to obtainthe phosphor having the emission spectrum with a broad peak in the rangefrom yellow color to red color (580 nm to 680 nm), and having anexcellent excitation band in the longer wavelength side in the rangefrom a near ultraviolet/ultraviolet as an excitation light to a visiblelight (250 nm to 550 nm). Recently, the phosphors are proposed such asan oxynitride glass phosphor capable of obtaining a broad emission peakin the range of yellow color to red color (for example, see patentdocument 1), a sialon-based phosphor (for example, see patent documents2 and 3), and the phosphor containing nitrogen such as siliconnitride-based phosphor (for example, see patent documents 4 and 5), Thephosphor containing nitrogen as described above has a larger ratio ofconvalent bonds, compared with the oxide-based phosphor, and thereforehas an excellent excitation band even in the light of 400 nm or morewavelength. Therefore, the phosphor containing the nitrogen is focusedas a phosphor for a white LED illumination.

The inventors of the present invention also propose the phosphor havingthe emission spectrum with an excellent excitation band in thewavelength range from the near ultraviolet/ultraviolet to visible light(250 nm to 550 nm) and a broad peak in the range from yellow color tored color (580 nm to 680 nm), and containing nitrogen (Japanese PatentApplication NO. 2004-55536).

-   (Patent document 1) Japanese Patent Laid Open No. 2001-214162-   (Patent document 2) Japanese Patent Laid Open No. 2003-336059-   (Patent document 3) Japanese Patent Laid Open No. 2003-124527-   (Patent document 4) Japanese Patent Laid Open No. 2003-515655-   (Patent document 5) Japanese Patent Laid Open No. 2003-277746

However, although the phosphor proposed by the inventors of the presentinvention is improved in the point of having the emission spectrum witha broad peak in the range from yellow color to red color (580 nm to 680nm) and an excellent excitation band in the longer wavelength side inthe range from a near ultraviolet/ultraviolet as an excitation light toa visible light (250 nm to 550 nm), the problem is involved therein suchthat the emission intensity is not a satisfactory level. Therefore, evenwhen the white LED illumination is manufactured by combining the nearultraviolet/ultraviolet LED and the blue LED, the mixing ratio of onlyred phosphor must be increased, thereby making the green phosphor or thelike insufficient to improve the luminance, and in some cases, a highluminance white color can not be obtained.

Therefore, the inventors of the present invention prepare samples ofvarious phosphors, while pursuing the cause of not obtaining asufficient emission intensity in the phosphor, and come to anunderstanding that a melting point of the raw material to be used ishigh, thereby making it difficult to progress a solid reaction,resulting in a non-uniform reaction.

SUMMARY OF THE INVENTION

In view of the above-described problem, the present invention isprovided, and an object of the present invention is to provide aphosphor having an emission spectrum with a broad peak in a range fromyellow color to red color (580 nm to 680 nm) and an excellent excitationband in a longer wavelength side, and improved in an emission intensity.

One of other object of the present invention is to provide amanufacturing method of the phosphor having the emission spectrum with abroad peak in the range from yellow color to red color (580 nm to 680nm) and the excellent excitation band in the longer wavelength side inthe range from a near ultraviolet/ultraviolet as an excitation light toa visible light (250 nm to 550 nm), and capable of improving theemission intensity.

The other object of the present invention is to provide a light sourceusing the phosphor having the emission spectrum with a broad peak in therange from yellow color to red color (580 nm to 680 nm) and theexcellent excitation band in the longer wavelength side in the rangefrom a near ultraviolet/ultraviolet as an excitation light to a visiblelight (250 nm to 550 nm), and capable of improving the emissionintensity.

The inventors of the present invention further study on the phosphor toaccelerate a progress of the solid reaction and realize a uniformreaction, and come to the understanding that boron and/or fluorine mustbe contained in the phosphor, and further come to the understanding thatthe content of an element Fe in the phosphor must be decreased.

Therefore the present invention takes several aspects as follows.

In a first aspect, a phosphor is provided, which is given by a generalcomposition formula expressed by MmAaBbOoNn:Z, (wherein element M ismore than one kind of element having bivalent valency, element A is morethan one kind of element having tervalent valency selected from thegroup consisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb, and Bi, element Bis more than one kind of element having tetravalent valency, O isoxygen, N is nitrogen, and element Z is more than one kind of elementselected from rare earth elements or transitional metal elements,satisfying m>0, a>0, b>0, o≧0, and n=2/3m+a+4/3b−2/3o), and furthercontaining boron and/or fluorine.

In a second aspect, the phosphor according to the first aspect isprovided, wherein a content of the boron is not less than 0.001 wt %,and not more than 3.0 wt %.

In a third aspect, the phosphor according to either of the first orsecond aspect is provided, wherein the content of the fluorine is notless than 0.1 wt %, and not more than 3.0 wt %.

In a fourth aspect, the phosphor according to any one of the firstaspect to third aspect is provided, wherein the values of the m, a, bare set so as to satisfy m=a=b=1, and o=0.

In a fifth aspect, the phosphor according to any one of the first tofourth aspects is provided, wherein the element M is more than one kindof element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn,the element A is more than one kind of element selected from the groupconsisting of Al and Ga, the element B is Si and/or Ge, and the elementZ is more than one kind of element selected from the rare earth elementsand the transitional metal elements.

In a sixth aspect, the phosphor according to any one of the first tofifth aspects is provided, wherein the element M is Ca, the element A isAl, the element B is Si, and the element Z is Eu.

In a seventh aspect, the phosphor according to any one of the first tosixth aspects is provided, wherein the content of the element Fe issmaller than 200 ppm.

In an eighth aspect, the phosphor according to any one of the first toseventh aspect is provided, wherein the phosphor is in a powdery state.

In a ninth aspect, the phosphor according to the eighth aspect isprovided, wherein an average particle size of the phosphor is not morethan 20 μm and not less than 0.1 μm.

In a tenth aspect, the phosphor according to the eighth aspect isprovided, wherein a specific surface area of the phosphor powder is notmore than 50 m²/g and not less than 0.1 m²/g.

In an eleventh aspect, a manufacturing method of the phosphor having thestructure according to any one of the first to tenth aspects isprovided, comprising:

weighing and mixing a compound containing the element M, the compoundcontaining the element A, and the compound containing the element Z or asimple substance of the element Z, and a boron compound and/or afluorine compound, to obtain a mixture;

firing the mixture, to obtain a fired object; and

pulverizing the fired object, to obtain the phosphor.

In a twelfth aspect, the manufacturing method of the phosphor accordingto the eleventh aspect is provided, wherein the compound containing theelement M, the compound containing the element A, the compoundcontaining the element B, and the compound containing the element Z or asimple substance of the element Z, and the compound of 100 ppm or lesscontent of Fe as the boron compound and/or the fluorine compound areused.

In a thirteenth aspect, the manufacturing method of the phosphoraccording to the twelfth aspect is provided, wherein as a compoundcontaining the element M, the nitride of the Group II expressed by thegeneral formula M₃N₂ containing 100 ppm or less of element Fe (whereinthe element M is more than one kind of element selected from the groupconsisting of Mg, Ca, Sr, Ba, and Zn.) is used.

In a fourteenth aspect, the manufacturing method of the phosphoraccording to the thirteenth aspect is provided, wherein the nitride ofthe Group II element manufactured by nitriding a simple substance of 2Nor more containing 100 ppm or less Fe is used, in a nitrogen atmosphereor in an ammonia atmosphere at the temperature of 300° C. or more.

In a fifteenth aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to fourteenth aspects is provided,wherein AlN having an average particle size of 0.1 μm to 5.0 μm is usedas the compound containing the element A, and Si₃N₄ having the averageparticle size of 0.1 μm to 5.0 μm is used as the compound containing theelement B.

In a sixteenth aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to fifteenth aspects is provided,wherein the boron compound is BN and/or H₃BO₃.

In a seventeenth aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to fifteenth aspects is provided,wherein the fluorine compound is CaF₂ and/or AlF₃.

In an eighteenth aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to seventeenth aspects is provided,wherein any one of the nitrogen atmosphere, the ammonia atmosphere, amixed gas atmosphere of nitrogen and hydrogen, and the mixed gasatmosphere of the nitrogen and ammonia is used, in the step of obtaininga fired object by firing the mixture.

In a nineteenth aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to seventeenth aspects is provided,wherein a nitrogen gas of 80% or more concentration is used, as anatmosphere gas during firing, in the step of obtaining the fired objectby firing the mixture.

In a twentieth aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to nineteenth aspects is provided,wherein the mixture is fired while ventilating the atmosphere gas at therate of 0.01 L/minor more, in the step of obtaining the fired object byfiring the mixture.

In a twenty-first aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to twentieth aspect is provided,wherein the temperature is set at not less than 1200° C. and not morethan 1600° C. during firing, in the step of obtaining the fired objectby firing the mixture.

In a twenty-second aspect, the manufacturing method of the phosphoraccording to any one of the eleventh to twenty-first aspect is provided,wherein a pressurizing state of the atmosphere gas during firing is setat not less than 0.001 MPa and not more than 0.1 MPa.

In the twenty-third aspect, a light source is provided, comprising thephosphor according to any one of the first to tenth aspects, and a lightemitting part.

In a twenty-fourth aspect, the light source according to thetwenty-third aspect is provided, wherein a wavelength range of lightemitted from the light emitting part is 250 nm to 550 nm.

In a twenty-fifth aspect, the light source according to either of thetwenty-third aspect or the twenty-fourth aspect is provided, wherein anLED (light emitting diode) is used as the light emitting part.

According to the phosphor of any one of the first to tenth aspects, thephosphor expressed by the composition formula MmAaBbOoNn:Z (wherein theelement M is more than one kind of element having bivalent valency, theelement A is more than one kind of element having tervalent valencyselected from the group consisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb,and Bi, the element B is more than one kind of element havingtetravalent valency, O is oxygen, N is nitrogen, and the element Z ismore than one kind of element selected from the rare earth elements orthe transitional elements, further satisfying m>0, a>0, b>0,n=2/3m+a+4/3b−2/3o) has excellent emission characteristics that a peakwavelength of the light emission is in the range from 580 nm to 680 nmand the emission spectrum has a half value width of 50 nm or more, andfurther has excitation band characteristics of having the emissionspectrum with a flat and high efficient excitation band in a broadwavelength range from the ultraviolet to the visible light (wavelengthrange from 250 nm to 550 nm).

In addition, since the phosphor contains the boron and/or fluorine, aproducing temperature of a liquid phase generated during firing isdecreased, and the solid reaction is uniformly progressed. Therefore,the emission intensity of the phosphor can be improved.

Further, when the phosphor contains not less than 0.001 wt % and notmore than 3.0 wt % of boron, and contains not less than 0.1 wt % and notmore than 3.0 wt % of fluorine, the producing temperature of the liquidphase generated during firing is decreased, and the solid reaction ismore uniformly progressed, and in addition, a violent sintering can besuppressed. Therefore, the emission efficiency of the phosphor can befurther improved.

The phosphor according to any one of the eighth aspect to tenth aspectis in a powdery state, and therefore coating and filling of the phosphorcan be easily performed. Further, since the average particle size of thephosphor powder is not more than 20 μm and not less than 0.1 μm, and thespecific surface area is not more than 50 m²/g and not less than 0.1m^(2/)g, the emission efficiency can be improved.

According to the manufacturing method of the phosphor of any one of theeleventh to twenty-second aspects, by adding the boron compound such asBN and H₃BO₃ as an additive agent other than the raw material of thephosphor, the producing temperature of the liquid phase generated in theprocess of the solid phase reaction is decreased, and the phosphorhaving an improved emission efficiency can be manufactured.

Also, by adding the fluorine compound such as CaF₂ and AlF₃ as theadditive agent other than the raw material of the phosphor, theproducing temperature of the liquid phase generated in the process ofthe solid phase reaction can be decreased, and the phosphor having theimproved efficiency can be manufactured.

According to the manufacturing method of the phosphor of the fifteenthaspect, by using AlN and Si₃N₄ with average particle size (D50) from 0.1μm to 10.0 μm, the phosphor with particle size suitable for coating andfilling, and further suitable for improving the emission intensity canbe manufactured.

According to the manufacturing method of the phosphor of the twentiethaspect, the phosphor capable of suppressing adsorption of the oxygenduring firing and decreasing the oxygen concentration of the phosphorand having suitable particle size for improving the emission intensitycan be manufactured.

The light source according to any one of the twenty-third totwenty-fifth aspects emits light, having the excitation band in apredetermined broad wavelength range (250 nm to 550 nm) of the lightemitted from the light emitting part (corresponding to LED according tothe twenty-fifth aspect). Therefore, by combining the aforementionedphosphors and the light emitting part, the light source with highemission efficiency emitting the visible light or the white light can beobtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a boron content and emission characteristicsor the like in Ca_(0.985)AlSiN₃:Eu_(0.015), which is an example of aphosphor according to the present invention.

FIG. 2 is a graph showing the relation between the boron content and arelative emission intensity in the phosphor of FIG. 1.

FIG. 3 is a diagram showing a fluorine content and the emissioncharacteristics or the like in Ca_(0.985)AlSiN₃:Eu_(0.015), which is anexample of a phosphor according to the present invention.

FIG. 4 is a graph showing the relation between the fluorine content andthe relative emission intensity in the phosphor of FIG. 3.

FIG. 5 is an emission spectrum of the phosphor according to an exampleand a comparative example of the present invention.

FIG. 6 is a graph showing Fe concentration and the relative emissionintensity according to the example and the comparative example of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereafter, preferred embodiments of the present invention will beexplained.

The preferred embodiments of the present invention provide a phosphorhaving an emission spectrum with a broad peak of 50 nm or more halfvalue width in a range from yellow color to red color (580 nm to 680 nm)and a flat and highly efficient excitation band, which is the range fromthe near ultraviolet/ultraviolet as an excitation light to visible light(250 nm to 550 nm) on the longer wavelength side, and further capable ofobtaining an excellent emission intensity by containing boron and/orfluorine in the phosphor, and a manufacturing method therefore.

In the phosphor having not less than 0.001 wt % and not more than 3.0 wt% of boron content, excellent emission characteristics can be obtained.The boron content is more preferably in the range from 0.05 wt % to 2.0wt %, and further preferably in the range from 0.15 wt % to 0.35 wt %.Although a detailed reason is not clarified, generally nitride has ahigh melting point, and hardly generates a liquid phase during solidreaction. Therefore, in many cases, the reaction does not progresssmoothly. However, in the phosphor containing the boron, the producingtemperature of the liquid phase is decreased and the liquid phase iseasily generated, thereby accelerating the reaction, further making thesolid reaction uniformly progress, and the phosphor having the excellentemission characteristic can be obtained.

When the boron content is not more than 3.0 wt %, sintering does notbecome violent, thereby not reducing the emission characteristic in apulverizing process. Further, when not more than 3.0 wt % of boron iscontained, a matrix structure exhibiting an excellent emission intensitycan be maintained, and this is considered to be preferable. Also, whenthe boron content is not less than 0.001 wt %, the liquid phase issufficiently produced, and a desired effect can be obtained.

Also, in the phosphor having the fluorine content of not less than 0.1wt % and not more than 3.0 wt %, the excellent emission intensity can beobtained. More preferably, the fluorine content is in the range from0.01 wt % to 2.0 wt %. Detailed reasons are not clarified. However, thecause is also considered as follows. A lot of nitrides have generallyhigh melting points, thereby hardly generating the liquid phase duringthe solid reaction, preventing the reaction from progressing. Meanwhile,in the fluorine content, in the same way as the case of the boroncontent, the producing temperature of the liquid phase is decreased,thereby easily generating the liquid phase, accelerating the reaction,and further making the solid reaction uniformly progress, and thephosphor having the excellent emission characteristic can be obtained.

When the fluorine content is not more than 3.0 wt %, the sintering doesnot become violent and the emission characteristic is not reduced in thepulverizing process. Therefore, the desired effect can be obtained.Further, when the fluorine content is not more than 3.0 wt %, animpurity phase not contributing to the light emission is not generated,thereby not inviting a reduction in the emission characteristic, andthis is considered to be preferable. Also, when the fluorine content isnot less than 0.1 wt %, the liquid phase is sufficiently generated, andthe desired effect can be obtained.

In the phosphor of this example, it is satisfactory to have cases suchas not only the case in which the boron and the fluorine are singlycontained respectively, but also the case in which not less than 0.001wt % and not more than 3.0 wt % of boron, and not less than 0.1 wt % andnot more than 3.0 wt % of fluorine are contained.

Also, the phosphor according to this example is expressed by thecomposition formula MmAaBbOoNn:Z. Here, the element M is more than onekind of element having bivalent valency, the element A is more than onekind of element having tervalent valency selected from the groupconsistsing of Al, Ga, In, Tl, Y, Sc, P, As, Sb, and Bi, the element Bis more than one kind of element having tetravalent valency, O isoxygen, N is nitrogen, and element Z is more than one kind of elementselected from rare earth elements or transitional metal elements.

Further, when the phosphor of the composition formula MmAaBbOoNn:Z has achemically stable composition, the impurity phase not contributing tothe light emission is hardly generated in the phosphor, thus suppressingthe deterioration in the emission characteristic to realize a preferablestructure. Therefore, in order to obtain a chemically stable compositionof the phosphor, preferably the phosphor satisfies the relationexpressed by m>0, a>0, b>0, o≧0, n=2/3m+a+4/3b−2/3o, and furtherpreferably the relation of m, a, and b satisfies m/(a+b)≦1/2, in theaforementioned composition formula MmAaBbOoNn:Z.

Further, in the phosphor having the composition of the aforementionedcomposition formula MmAaBbOoNn:Z, the element M is the element having +bivalent valency, the element A is the element having + tervalentvalency, the element B the element having + tetravalent valency, oxygenis the element having − bivalent valency, and nitrogen is the elementhaving − tervalent valency. Therefore, when m, a, b, and n satisfy thecomposition expressed by n=2/3m+a+4/3b−2/3o, the valency of each elementis added to be zero, thus preferably realizing a further stable compoundin the composition of the phosphor. Particularly, when the relation ofm, a, b, and n satisfies m:a:b:n=1:1:1:3 (and o=0), the phosphor havingexcellent emission characteristic and excitation band characteristic isobtained.

In any case, a slight deviation of the composition from theaforementioned composition formula showing the composition of thephosphor of the present invention is allowable. For example, thephosphor prepared satisfying m a:b:n=1:1:1:3 does not basically containoxygen. However, the aforementioned phosphor sometimes contains theoxygen. The oxygen in this case is considered to be the oxygen initiallycontained in the raw material and the oxygen adhered to the surface ofthe raw material, and the oxygen mixed in resulting from the oxidizationof the surface of the raw material during mixing and firing the rawmaterials, and the oxygen adsorbed on the surface of the phosphor afterfiring. As a result, in some cases, the oxygen of 3.0 wt % or less iscontained with respect to the mass of the phosphor. However, preferablythe oxygen content of the phosphor has an upper limit set at theaforementioned 3.0 wt %, thereby being set at not more than this upperlimit value.

Preferably, the element M is at least more than one kind of elementselected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, andHg, further preferably is more than one kind of element selected fromthe group consisting of Mg, Ca, Sr, Ba, and Zn, and most preferably isCa.

Preferably the element A is at least more than one kind of elementhaving tervalent valency selected from the group consisting of Al, Ga,In, T i, Y, Sc, P, As, Sb, and Bi, further preferably is more than onekind of element selected from Al and Ga, and most preferably is Al. Outof these elements, Al is easily available at a low cost, with smallenvironmental load, and preferable. Particularly, AlN, which is anitride, is used as a thermoelectric material and a structural materialgenerally used.

Preferably, the element B is more than one kind of element havingtetravalent valency selected from the group consisting of C, Si, Ge, Sn,Ti, Hf, Mo, W, Cr, Pb, and Zr, further preferably is Si and/or Ge, andmost preferably is Si. Out of these elements, Si is easily available ata low cost, with small environmental load, and preferable. Particularly,Si₃N₄, which is a nitride, is used as the thermoelectric material andthe structural material generally used.

Preferably, the element Z is more than one kind of element selected fromthe rare earth elements and the transitional metal elements. However, inorder to exhibit an excellent color rendering property in anillumination device and a light emitting device using the phosphor,preferably the light emission of the phosphor has the emission spectrumwith a broad half value width. Then, from this viewpoint, the element Zis preferably at least more than one kind of element selected from thegroup consisting of Eu, Mn, Sm, and Ce. Out of these elements, when Euis used as the element Z, the phosphor exhibits a high emissionefficiency in the range from orange color to red color, and the spectrumwith a broad half value width of 50 nm or more can be obtained.Therefore, Eu is more preferable as the activator of the phosphor usedin the illumination device and the light emitting device.

Incidentally, in accordance with the kind of the element Z substitutinga part of the element M of the composition of the phosphor, the phosphorhaving the light emission with different wavelength can be obtained.

When the phosphor is expressed by MmAaBbOoNn:Zz, preferably the amountof the element Z to be added is in such a range as satisfying the molarratio of the element M to the element Z, z/(m+z), being in the rangefrom 0.0001 to 0.5. When the molar ratio z/(m+z) of the element M andthe activator z is within the aforementioned range, the deterioration inthe emission efficiency resulting from the concentration quenching dueto an excessive content of the activator can be avoided, and meanwhile,the deterioration in the emission efficiency resulting from insufficientemission contributing atoms due to too little content of the activatorcan also be avoided. In addition, more preferably the value of theaforementioned z/(m+z) is in the range from 0.005 to 0.1. However, anoptimal value of the aforementioned z/(m+z) is slightly fluctuated bythe kind of the activator Z and the kind of the element M. Further, bycontrolling the amount of the activator Z to be added also, the peakwavelength of the emission spectrum of the phosphor can be set byshifting, which is useful for adjusting the luminance.

When the phosphor of this example is used in the form of a powder, it ispreferable to set the average particle size (D50) of the phosphor powderat not more than 20 μm. This is because by setting the average particlesize (the average particle size in this invention refers to a mediandiameter (D50).) at not more than 20 μm, and further preferably set atnot less than 3 μm and not more than 15 μm, the surface area per unitweight of the powder can be secured, and the deterioration in theluminance can be avoided, because the light emission in the phosphorpowder is considered to occur on the surface of the particle. Further,the powder is formed into paste, and when the paste thus formed isapplied to the light emitting element or the like also, the density ofthe powder can be heightened, and from this viewpoint also, thedeterioration in the luminance can be avoided. In addition, according tothe study of the inventors of the present invention, although a detailedreason is not clarified, it was found that preferably the averageparticle size was larger than 0.1 μm from the viewpoint of the emissionefficiency of the phosphor powder. As described above, the averageparticle size of the phosphor powder in this example is preferably setat not less than 0.1 μm and not more than 20 μm.

When the phosphor of this example is manufactured, as the raw materialsof the element M (+ bivalent valency), the element A (+ tervalentvalency), and the element B (+ tetravalent valency), the nitride andoxide of each of them and the compound of any one of them may be used.For example, the nitride (M₃N₂) and the oxide (MO) of the element M, andthe nitride (AN, B₃N₄) of the element A and the element B may be usedand mixed. Then, by controlling the blending ratio of both of thenitride and the oxide, an amount of oxygen and an amount of nitrogen inthe phosphor can be controlled, without changing the value of m. Ofcourse, the nitride and the oxide are not limited to the compoundobtained by combining with only oxygen and the compound obtained bycombining with only nitrogen, but for example, refers to the compoundhaving the oxygen and the element, such as carbonate acid salt andoxalic acid salt, which are decomposed to become substantially oxideduring firing, and the nitride also refers to the compound having theelement and the nitrogen.

However, for convenience of explanation hereunder, as the compoundhaving the aforementioned element and the oxygen, and as the compoundhaving the aforementioned element and the nitrogen, by way of example,the oxide of the aforementioned element and the nitride of theaforementioned element will be explained, respectively.

For example, when the raw materials are measured under the condition ofo=0, m=a=b=1, each raw material may be weighed at the molar ratio ofM₃N₂:AN:B₃N₄=1:3:1. Further, in this condition, when the element Z isthe element having bivalent valency, the element Z substitute a part ofthe element M. Therefore, in consideration of this substitution,preferably the phosphor is expressed by MmAaBbNn:Zz, satisfying(m+z)=a=b=1. The chemically stable composition of the phosphor isthereby obtained.

Further, in this example, it was found that the emission characteristicwas improved by adding a boron compound and a fluorine compound asadditive agents. In this case, the boron compound, such as BN, H₃BO₃,B₂O₆, B₂O₃, and BCl₃, may be added to obtain not more than 3.0 wt % ofthe boron in the sample after firing, and out of these elements, BN andH₃BO₃ are preferable. Such boron compounds may be mixed for use. Theboron compound has high thermal conductivity. Therefore, by adding theboron compound to the raw material, a uniform temperature distributionof the raw material during firing is obtained, and it is estimated thatthe emission characteristic is improved to accelerate the solid phasereaction. The boron compound can be added to the raw material in such amanner that it is added together with the raw materials during mixing soas to be mixed therein.

Also, preferably the fluorine compound, such as CaF₂, AlF₃, EuF₂, EuF₃is added to obtain not more than 3.0 wt % of fluorine in the sampleafter firing. Such fluorine compounds have low melting points comparedto those of raw materials, AlN and Si₃N₄, thereby easily generating aliquid phase. Therefore, by covering the surface of the surface of theparticle of the raw material, it appears that diffusion of atoms can beaccelerated, and the emission characteristic is thereby improved.Moreover, the fluorine compound obtained by combining the fluorine andcalcium, the fluorine and aluminum, and the fluorine and europium ispreferably added to the phosphor in which the element M is Ca, theelement A is Al, the element B is Si, and the element Z is Eu, becausethe same element is contained therein as the element having theaforementioned composition formula. Such fluorine compounds may also bemixed for use.

Amounts of the boron and the fluorine to be added to such raw materials,and contents of the boron and fluorine after firing are not alwaysmatched. This is because some of the boron and the fluorine is flownduring firing, and therefore the content thereof becomes smaller thanthat at the time of addition of the raw materials, or a slight amount ofboron and fluorine is contained in each raw material also, and thereforethe content thereof becomes larger than that at the time of adding theraw materials. Note that for convenience of explanation, the oxygen inthe composition formula is omitted in the explanation given hereunder.

Next, the manufacturing method of the phosphor in this example will beexplained, with manufacture of Ca_(0.985)AlSiN₃:Eu_(0.0150) given as anexample.

Each nitride raw material of the element M, the element A, and theelement B may be a commercially available raw material. However, higherpurity is more preferable, and therefore preferably the nitride rawmaterial of 2N or more, and more preferably 3N or more is prepared.Further, it becomes possible to prepare the phosphor with excellentemission efficiency, by using the raw material having not more than 100ppm of element Fe contained therein, as the nitride raw material of eachelement.

Here, explanation will be given to a case where the nitride raw materialhaving the element Fe of not more than 100 ppm is used.

The nitride of the element M, such as conventionally available Ca₃N₂contains the element Fe of about 250 ppm.

Therefore, preferably the nitride raw material of the element M of thephosphor according to the present invention is used, which ismanufactured by the following method, for example.

First, a simple substance of the element M of 2N or more and having thecontent of the element Fe of 100 ppm or less is prepared. Some of simplesubstances of the alkali-earth metal have oil films on the surface whichare stuck during storage. Therefore, the surface of the simple substanceof alkali-earth metal is washed with organic solvent in an inert gasatmosphere. The metal body thus washed is heated and nitrided at thetemperature of 300° C. or more in the atmosphere of nitrogen or ammonia,to thereby manufacture the nitride. Preferably, a vessel or a crucibleused at the time of nitriding is the vessel having a small content ofthe element Fe, and specifically a BN crucible with high purity ispreferable. Also, preferably a heating temperature for nitriding is notless than 700° C., because the nitriding is accelerated by a highertemperature. The nitride of the element M thus obtained may bepulverized to not more than 100 μm degree of particle for use.

The nitride of the element A and the nitride of the element B are alsoobtained by nitriding the metal element in the same method. However, inregards to the nitride of the element A, such as AlN, even theconventionally available one has the content of the element Fe of about10 ppm or less, and therefore such a nitride of the element A may beused.

Also, in regards to the nitride of the element B, such as Si₃N₄, theconventionally available one has the content of the element Fe of about50 ppm or less, and therefore such a nitride of the element B may alsobe used.

Next, the particle size and shape of each nitride raw material will beexplained.

It is preferable to prepare the nitride raw material having the particlesize and shape approximated the particle size and shape desired for thephosphor finally obtained. As described above, the average particle sizedesired for the phosphor is preferably from 0.1 μm to 20.0 μm, and morepreferably from 3.0 μm to 15.0 μm. Therefore, from the viewpoint ofcontrolling the particle size of the phosphor powder after firing, it ispreferable to set the average particle size of each raw material at 0.1μm to 5.0 μm. Here, although it is preferable to set the averageparticle size of all the raw materials at 0.1 μm to 5.0 μm, the phosphorhaving the excellent emission characteristic can be manufactured byusing at least AlN and Si₃N₄ having the aforementioned particle size,because AlN and Si₃N₄ mainly form the matrix structure and have highmelting temperature. When the raw material has the average particle sizeof not less than 0.1 μm, such a raw material is hardly sintered and theemission intensity is not decreased in a pulverizing process afterfiring. In addition, a uniform reaction is obtained, in case of the rawmaterial of not more than 20.0 μm, and this is preferable. Similarly,average sizes of the raw material of the element Z as will be describehereunder and the raw material of an additive are also preferably set at0.1 μm to 20.0 μm, and more preferably set at 1.0 μm to 5.0 μm.

The raw material of the element Z may also be the conventionallyavailable nitride raw material or the oxide raw material. In this casealso, the higher purity is preferable, and therefore the raw material ofthe element Z is preferably set at not less than 2N, and more preferablyset at not less than 3N, and the raw material thus set is prepared. Notethat the oxygen contained in the oxide raw material is also supplied tothe composition of the phosphor, and therefore it is preferable toconsider the oxygen supply amount when examining the blending ratio ofthe raw materials such as the aforementioned element M, element A, andelement B. Then, when the oxygen is desired to be contained in thecomposition of the phosphors as less as possible, a simple substance ofthe element Z or the nitride of the element Z may be used as the rawmaterial.

The raw material of the additive may also be the conventionallyavailable boron compound or the fluorine compound. In this case also,the higher purity is preferable, and therefore the raw material of theadditive is also preferably set at not less than 2N, and more preferablyset at not less than 3N, and the raw material thus set is prepared.

In the manufacture of Ca_(0.985)AlSiN₃:Eu_(0.0150), for example, as thenitride of the element M, the element A, and the element B, Ca₃N₂(2N),AlN(3N), and Si₃N₄(3N) may be prepared, respectively. As the element Z,Eu₂O₃(3N) is prepared and as the additive, the boron compound and/orfluorine compound are prepared.

These raw materials are weighed to obtain the mixing ratio of 0.985/3mol of Ca₃N₂, 1 mol of AlN, 1/3 mol of Si₃N₄, and 0.015/2 mol of Eu₂O₃,so that the molar ratio of each element is expressed byCa:Al:Si:Eu=0.985:1:1:0.015. Further, an arbitrary amount of theadditive is also weighed and mixed.

In order to prevent the oxidization of the nitride, i.e. the rawmaterial, it is convenient to perform the weighing and mixing in a glovebox under the inert atmosphere. Moreover, the nitride raw material ofeach element is liable to be affected by oxygen and moisture. Therefore,preferably the inert gas from which the oxygen and the moisture aresufficiently removed is used. When the nitride raw material is used, adry type mixing is preferable as a mixing system to obviate adecomposition of the raw material, and a usual dry type mixing systemusing a ball mill and a mortar may be selected. Note that when theorganic solvent capable of preventing the decomposition of the rawmaterial is used, a wet type mixing is also selected. Further, from theviewpoint of reducing the content of the element Fe, it is alsopreferable to use the solvent not containing the element Fe as thesolvent containing the aforementioned organic solvent, in order toprevent mix-in of the element Fe during mixing.

The raw material thus mixed is put in a crucible, retained in any one ofthe gas atmosphere such as inert atmosphere of nitrogen or the like,ammonia atmosphere, mixed gas atmosphere of nitrogen and hydrogen, andmixed gas atmosphere of nitrogen and ammonia at 1000° C. or more,preferably at 1200° C. or more and 1600° C. or less, further preferablyat 1400° C. or more and 1600° C. or less, for more than 30 minutes andpreferably for 3 hours or more, and fired, with the inside of thefurnace pressurized. The higher the firing temperature is, the morerapidly the reaction is progressed, and the retaining time is thereforeshortened. Meanwhile, even when the firing temperature is low, thetarget emission characteristic can be obtained by maintaining thetemperature for a long time. However, the longer the firing time is orthe higher the firing temperature is, the more rapidly a particle growthis advanced, and the particle size becomes therefore large. Therefore,the firing time and the temperature may be set in accordance with thetarget particle size.

In the manufacture of the nitride phosphor, it is preferable to take amethod of preventing the mix-in of the oxygen over the entire processes.First, the oxygen in the raw material and the oxygen stuck to thecrucible or the like are taken into consideration as a factor of themix-in of the oxygen. Therefore, the oxygen thus mixed-in needs to bereduced. However, it is hardly possible to remove all the oxygen.Therefore, by selecting the high temperature reductive gas atmosphere asthe gas atmosphere for firing the raw material, the oxygen accompanyingthe decomposition and nitriding of the raw material can be removed.After studying on the reducing method of the remaining amount of theoxygen in the phosphor after firing, the inventors of the presentinvention found that during firing, there was a possibility that theoxygen stuck to the raw material such as Eu₂O₃ is released from theoutside of a raw material crystal and combined with the crystal phase ofthe phosphor, and came to the system of ventilating the atmosphere gasduring firing, to prevent the oxygen from combining to the crystal phaseof the phosphor. Then, the result is obtained, such that less amount ofoxygen is mixed-in in the phosphor manufactured by ventilating theatmosphere gas compared with the phosphor manufactured withoutventilating the atmosphere gas, and the emission characteristic of thephosphor could be improved. Then, it is effective to continuouslyventilate the gas atmosphere after initial period of firing, at aventilation amount of 0.01 ml/min or more. However, more preferably thegas ventilation amount is 0.1 ml/min or more, and most preferably 1.0L/min or more.

In the same way as the aforementioned atmosphere gas, the gas forventilation may be any one of the inert gas such as nitrogen, theammonia gas, the mixed gas of the nitrogen and the hydrogen, and themixed gas of the nitrogen and the ammonia. However, an oxidizationreaction of the phosphor occurs, when the oxygen is contained therein,and therefore preferably the oxygen or the moisture mixed-in as animpurity is 100 ppm or less. In addition, when the mixed gas of thenitrogen and other gas is used from the viewpoint of smoothlyaccelerating a nitriding reaction of the phosphor, it is preferable toset the concentration of nitrogen in the mixed gas at 80% or more.

The pressure in the furnace is preferably set in a pressurized state,after preventing the oxygen in the atmospheric air from mixing-in thefurnace, and when the pressure in the furnace is set at 0.5 MPa (5.0kgf/cm²) or less, the phosphor having a sufficiently satisfactorycharacteristic can be obtained.

From the viewpoint of requiring a special pressure resistance in termsof designing a furnace facility when the pressure exceeds 0.1 MPa (1.0kgf/cm²), and from the view point of suppressing an excessiveacceleration of firing that occurs between phosphor powders andfacilitating the pulverizing after firing, the pressure is preferablyset at 0.001 MPa (0.01 kgf/cm²) or more and 0.1 Mpa (1 kgf/cm²) or less,and further preferably set at 0.001 Mpa (0.01 kgf/cm²) or more and 0.05Mpa (0.5 kgf/cm²) or less.

As the crucible, an Al₂O₃ crucible, Si₃N₄ crucible, an AlN crucible, asialon crucible, a C (carbon) crucible, and a BN (nitride boron)crucible, not containing impurities such as the element Fe and posing noproblem even in the inert gas atmosphere can be used. However, it ispreferable to use the BN crucible, because the mix-in of the impuritiesfrom the crucible can be prevented. Further, when the BN crucible isused, B is mixed-in from a part where the BN crucible and the rawmaterial are brought into contact with each other, even if not adding aBN powder. In this condition, the emission characteristic of thephosphor can be improved. However, mix-in of B occurs at one of the partwhere the BN and the crucible are brought into contact with each other.Therefore, there is less improvement, when compared to the case whereraw material powder and BN powder are mixed and B is mixed-in the wholearea. Namely, by using the BN crucible, B may be mixed-in. However morepreferably the BN powder and the raw material powder are mixed and B ismixed-in the whole area.

After firing is completed, a fired object is taken out from thecrucible, and pulverized up to a predetermined average particle size, tothereby obtain the phosphor expressed by the composition formulaCa_(0.985)AlSiN₃:Eu_(0.0150).

When other element is used as the element M, the element A, the elementB, and the element Z, and when the amount of Eu as the activator ischanged also, the phosphor having the predetermined composition formulacan be manufactured by the same manufacturing method as that describedabove, by adjusting the blending amount at the time of mixing each rawmaterial to a predetermined composition ratio.

As described above, the phosphor according to this embodiment theemission spectrum with an excellent excitation band in a broad rangefrom the ultraviolet to visible light (wavelength range from 250 nm to550 nm), and by this phosphor, the light source of high output andfurther an illumination unit including this light source can be obtainedby combining the phosphor of this example and the light emitting partemitting the aforementioned ultraviolet to visible light (LED lightemitting element as will be described later and a discharge lamp),because the emission intensity of the phosphor is high.

Namely, by combining the phosphor of this embodiment set in a powderystate with the light emitting part (particularly the light emitting partemitting the light having the wavelength range from 250 nm to 550 nm) bythe publicly-known method, various display devices and illuminationunits can be manufactured. For example, by combining the phosphor ofthis example and the discharge lamp emitting ultraviolet light, thefluorescent lamp and the illumination unit and the display device can bemanufactured. Also, by combining the phosphor of this example and anelectron beam generator, the display device can be manufactured.Further, by combining the phosphor of this example and the LED lightemitting element emitting ultraviolet to visible light as the lightemitting part, the illumination unit and the display device can bemanufactured.

The illumination unit thus manufactured has the emission spectrum with abroad peak in the range from yellow color to red color (580 nm to 680nm) and an excellent excitation band on the longer wavelength side fromthe near ultraviolet/ultraviolet, which is the range of the excitationlight, to the visible light (250 nm to 550 nm), and has an improvedemission intensity.

Particularly, in the white LED illumination obtained by combining thephosphor according to this example, the phosphor of other color (such asyellow phosphor), and a blue LED or an ultraviolet LED, the lightemitting device exhibiting a significantly preferable color renderingproperty having the average color rendering index Ra of 80 or more,particularly R15 of 80 or more, and R9 of 60 or more of the lightemitting device can be obtained, by mixing the phosphors according tothe present invention under the correlated color temperature of thelight emitting device set in the range from 7000K to 2500K. Furtherpreferably, when the light emitting device is caused to exhibit theaforementioned color rendering property, the blending amount of the redphosphor according to the present invention may be 20% or less withrespect to the phosphor of other color. As a result, the blending amountof the phosphor of other color can be gained, and this contributes toobtaining the light emitting device with excellent color renderingproperty having Ra set at 80 or more can be obtained, withoutdeteriorating the emission efficiency of the yellow phosphor or thelike.

EXAMPLE Comparative Example 1

As a comparative example 1, commercially available Ca₃N₂(2N), AlN(3N andhaving the average particle size of 1.76 μm), Si₃N₄(3N and having theaverage particle size of 0.774 μm), and Eu₂O₃ (3N) were prepared, andeach raw material was weighed to obtain 0.985/3 mol of Ca₃N₂, 1 mol ofAlN, 1/3 mol of Si₃N₄, and 0.015/2 mol of Eu₂O₃, and the raw materialsthus weighed were placed in the glove-box under the nitrogen atmosphereand mixed by using the mortar. The raw materials thus mixed were put ina Si₃N₄ crucible, and retained/fired for 3 hours at 1500° C. in thenitrogen atmosphere, with pressure in the furnace set at 0.5 kgf/cm .Thereafter, the temperature was cooled from 1500° C. to 200° C. for 1hour. Then, the raw materials were pulverized after firing, and thephosphor expressed by the composition formulaCa_(0.985)AlSiN₃:Eu_(0.015) was obtained. Note that this compositionformula is estimated from the raw material used and the blending ratio.

The phosphor thus obtained was irradiated with the excitation light ofmonochromatic light with 460 nm wavelength, and the emissioncharacteristic was measured. The peak wavelength in items of theemission characteristics refers to the wavelength of the peak wherehighest emission intensity is shown in the emission spectrum by nm unit.The emission intensity in the peak wavelength is shown by the relativeintensity, and the intensity of the comparative example 1 isstandardized as 100%. Chromaticity x, y is obtained by a calculationmethod defined by the JISZ8701. The boron concentration contained in aphosphor particle sample is the value obtained by measuring by anabsorption photometry.

The composition formula of the phosphor, an analysis result of the boronconcentration, emission characteristics (peak wavelength, emissionintensity, and chromaticity), and powder characteristics (particle sizeand specific surface area BET) are shown in FIG. 1.

Examples 1 to 4

In the examples 1 to 4, the phosphor sample is manufactured in the sameway as the comparative example 1, excepting that the boron nitride BN(3N) is added as the additive agent other than each raw material ofCa₃N₂(2N), AlN(3N), Si₃N₄(3N), and Eu₂O₃(3N), and the crucible ischanged from the Si₃N₄ crucible to a BN crucible.

Specifically, in the example 1, 0.1 wt % of BN powder is added in amixed raw material (before firing) of Ca_(0.985)AlSiN₃:Eu0.015.Similarly, 0.5 wt % of the BN powder is added in the example 2, 1.0 wt %of the BN powder is added in the example 3, and 2.0 wt % of the BNpowder is added in the example 4, respectively.

In the examples 1 to 4 also, in the same way as the comparative example1, the composition formula of the phosphor, the analysis result of theboron concentration, and the measurement result of the emissioncharacteristics (peak wavelength, emission intensity, and chromaticity)and the powder characteristics (particle size and specific surface areaBET) are shown in FIG. 1, and the relation between the boron content andthe relative emission intensity (the relative intensity of the emissionintensity of the comparative example 1 is defined as 100%) is shown inFIG. 2.

From FIG. 1, it is confirmed that by adding the BN powder, the boroncontent is increased. Although the boron content of the comparativeexample 1 is not more than 0.0001 wt %, the boron content is increasedwhen the BN powder is added in the examples 1 to 4, in such away that0.063 wt % of the boron content is obtained when 0.1 wt % of the BNpowder is added, 0.170 wt % of the boron content is obtained when 0.5 wt% of the BN powder is added, 0.310 wt % of the boron content is obtainedwhen 1.0 wt % of the BN powder is added, and 0.640 wt % of the boroncontent is obtained when 2.0 wt % of the BN powder is added.

Also, it is confirmed from FIG. 1 and FIG. 2, by containing the boron,the emission intensity is improved. The emission intensity is increasedhaving a peak in the range from 0.15 wt % to 0.35 wt % of the boroncontent, and is increased by 19.6% compared to that of the comparativeexample 1 without BN addition. In addition, by containing the boron, thepeak wavelength is liable to shift toward the longer wavelength side.Further, when the boron content is not more than 0.310 wt % (examples 1to 3), the average particle size is approximately the same as that ofthe comparative example 1 without BN addition. However, when the boroncontent is 0.640 wt % (example 4), the average particle size becomes10.58 μm, and two times of the size is obtained, compared to the size ofthe comparative example 1 (5.851 μm) without BN addition. From thisresult, in the phosphor containing the boron in a certain range, itappears that the reaction is accelerated, and the emission intensity isimproved.

Examples 5 to 7

In the examples 5 to 7, in the same way as the comparative example 1,the phosphor sample is manufactured by adding fluorine calcium CaF₂(3N)as an additive agent, in addition to each raw material of Ca₃N₂(2N),AlN(3N), Si₃N₄(3N), EU₂O₃(3N) explained in the comparative example 1,and further by changing the crucible from the Si₃N₄ crucible to the BNcrucible.

Specifically, in the example 5, 0.025 mol of CaF₂ is added to the rawmaterial, with which 1.0 mol of Ca_(0.985)AlSiN₃:Eu0.015 is obtained. Inthe same way, 0.050 mol of CaF₂ is added in the example 6, and 0.100 molof CaF₂ is added in the example 7.

In the comparative example 1 and the examples 5 to 7, the compositionformula of each phosphor, the analysis result of the fluorineconcentration, the measurement result of the emission characteristics(peak wavelength, emission intensity, and chromaticity) and the powdercharacteristics (particle size and specific surface area BET) are shownin FIG. 3, and the relation between the fluorine content and therelative emission intensity (the relative intensity of the emissionintensity of the comparative example 1 is defined as 100%) is shown inFIG. 4.

It is confirmed from FIG. 3 that the fluorine content is increased byadding CaF₂ powder. Although not more than 0.10 wt % of fluorine contentis contained in the comparative example 1, the fluorine content isincreased when CaF₂ powder is added in the examples 5 to 7,respectively, wherein 0.40 wt % of the fluorine content is obtained when0.025 mol of CaF₂ powder is added, 0.80 wt % of fluorine content isobtained when 0.050 mol of CaF₂ powder is added, and 1.70 wt % offluorine content is obtained when 0.100 mol of CaF₂ powder is added.

Also, in the same way as the case of the boron, it is confirmed fromFIGS. 3 and 4, that by containing the fluorine, the emission intensityis improved. The emission intensity is gradually improved up to 0.40 wt% of the fluorine content, and is decreased when the fluorine contentexceeds 0.40 wt %. Further, the emission intensity is improved having apeak at 0.40 wt % of the fluorine content, thereby showing 17.3% ofimprovement compared to case of the comparative example 1 without CaF₂addition. Further, by containing the fluorine, the peak wavelength isliable to shift toward the longer wavelength side. Further, when thefluorine content is not more than 1.70 wt %, the average particle sizewas the same as that of the comparative example 1 without BN addition.From this result, in the same way as the boron, in the phosphorcontaining the fluorine in a certain range also, it appears that thereaction is accelerated, and the emission intensity is improved.

Example 8

By the method explained in this embodiment, metal Ca with 99.5% ofpurity and 90 ppm content of the element Fe was heated in the nitrogenatmosphere at 700° C., then the metal thus heated was pulverized, andCa₃N₂ was thereby manufactured. The content of the element Fe of theCa₃N₂ thus manufactured was 60 ppm. The Ca₃N₂ thus manufactured andother raw materials are weighed to obtain the ratio of 0.980/3 mol ofCa₃N₂, 1/3 mol of Si₃N₄, 1 mol of AlN, and 0.020/2 mol of Eu₂O₃, thenmixed in the mortar and fired at 1600° C. for 3 hours with pressure of0.05 MPa in the nitrogen atmosphere, and a red phosphor CaAlSiN₃:Eu wasmanufactured. During firing, the nitrogen is ventilated at 1.0 L/min. Asshown in table 1, the contents of the element Fe of the Ca₃N₂, Si₃N₄,AlN, and Eu₂O₃ were 60 ppm, 20 ppm, 90 ppm, and 10 ppm, respectively.

FIG. 5 shows the emission spectrum of the phosphor powders manufacturedby the example 8 and the examples 9 to 10 as will be described later andthe comparative examples 2 to 4, respectively, showing the emissionwavelength taken on the abscissa axis, and the relative emissionintensity taken on the ordinate axis. In FIG. 5, the emission intensityof the example 8 is standardized as 1, and the relative emissionintensity of other example is obtained.

As shown by a thick line of FIG. 5, when the phosphor powder of theexample 8 thus obtained was irradiated with monochromatic light of 460nm wavelength, the phosphor powder emitted red light having the emissionspectrum with a peak at 656 nm and a half value width of 50 nm or more.In addition, as shown in table 1 and FIG. 6, the content of the elementFe, which is an impurity of the phosphor of the example 8, obtained bychemical analysis, was 100 ppm.

The aforementioned FIG. 6 shows the relative emission intensity to theconcentration of impurity element Fe of the phosphor manufactured by theexample 8, the examples 9 to 10 as will be described later, and thecomparative examples 2 to 4, wherein the emission intensity of theexample 8 is standardized as 1, and then the relative emission intensityof other example and comparative example is obtained.

Also, the table 1 shows the concentration of the impurity element Feobtained by the chemical analysis of Ca₃N₂(2N), Si₃N₄(3N), AlN(3N), andEu₂O₃(3N), which are raw materials of the phosphor manufactured in theexample and the comparative example, the relative emission intensity ofthe phosphor manufactured by the example and the comparative example,and the content of the impurity Element Fe obtained by the chemicalanalysis. The relative emission intensity of other example and thecomparative example is obtained by standardizing the emission intensityof the example 8 as 1. TABLE 1 Fe CONCENTRATION IN RAW MATERIAL PRODUCTCa₃N₂ Si₃N₄ AIN E₂O₃ Fe CONCENTRATION EMISSION INTENSITY (ppm) (ppm)(ppm) (ppm) (ppm) (RELATIVE INTENSITY) EXAMPLE 1 60 20 90 10 100 1.000EXAMPLE 2 27 20 90 10 80 1.035 EXAMPLE 3 70 20 90 10 120 0.977COMPARATIVE EXAMPLE 1 230 20 90 10 260 0.895 COMPARATIVE EXAMPLE 2 77020 90 10 400 0.872 COMPARATIVE EXAMPLE 3 1400 20 90 10 600 0.862

Example 9

As shown in the table 1, the red phosphor CaAlSiN₃:Eu was manufacturedunder the same condition as that of the example 8, other than usingCa₃N₂ raw material having lower content of the element Fe than that ofthe example 8. The contents of the element Fe of Ca₃N₂, Si₃N₄, AlN, andEu₂O₃ used in the raw materials were 27 ppm, 20 ppm, 90 ppm, and 10 ppm,respectively.

When the phosphor powder thus obtained was irradiated with themonochromatic light of 460 nm, as shown in a thick broken line of FIG.5, the phosphor powder emitted red light having the emission spectrumwith a peak at 656 nm and the half value width of 50 nm or more. Also,as shown in the table 1 and FIG. 6, the content of the impurity elementFe of the phosphor thus obtained by the chemical analysis was 80 ppm.

Example 10

As shown in the table 1, the red phosphor CaAlSiN₃:Eu was prepared underthe same condition as that of the example 8, other than using Ca₃N₂ rawmaterial having 10 ppm more content of the element Fe than that of theexample 8. The contents of the element Fe of the Ca₃N₂, Si₃N₄, AlN,Eu₂O₃ were 70 ppm, 20 ppm, 90 ppm, and 10 ppm.

When the phosphor powder thus obtained was irradiated with themonochromatic light of 460 nm, as shown by a thick two-dot line in FIG.5, the phosphor powder emitted red light having the emission spectrumwith a peak at 656 nm and a half value width of 50 nm or more. Also, asshown in the table 1 and FIG. 6, the content of the impurity element Feof the phosphor thus obtained by the chemical analysis was 120 ppm.

In the next comparative examples 2 to 4, the emission intensity of thephosphor was examined and compared to that of the examples 8 to 10, whenCa₃N₂ having more content of the element Fe than that used as the rawmaterial in the example.

Comparative Example 2

As shown in the table 1, the red phosphor CaAlSiN₃:Eu was prepared underthe same condition as that of the example 8, other than using Ca₃N₂ rawmaterial having 230 ppm content of the element Fe. The contents of theelement Fe of Si₃N₄, AlN, Eu₂O₃, which were other raw materials, were 20ppm, 90 ppm, and 10 ppm, respectively.

When the phosphor powder thus obtained was irradiated with themonochromatic light of 460 nm, as shown by a thin solid line of FIG. 5,the phosphor powder emitted red light having the emission spectrum witha peak at 656 nm and a half value width of 50 nm or more. Also, as shownin the table 1 and FIG. 6, the content of the impurity element Fe of thephosphor obtained by the chemical analysis was 260 ppm.

Comparative Example 3

As shown in the table 1, the red phosphor CaAlSiN₃:Eu was prepared underthe same condition as that of the example 8, other than using thecommercially available Ca₃N₂ raw material having 770 ppm content of theelement Fe. The contents of the element Fe of Si₃N₄, AlN, Eu₂O₃, whichwere other raw materials, were 20 ppm, 90 ppm, and 10 ppm, respectively.

When the phosphor powder thus obtained was irradiated with themonochromatic light of 460 nm, as shown by the thin broken line of FIG.5, the phosphor powder emitted red light having the emission spectrumwith a peak at 656 nm and a half value width of 50 nm or more. Also, asshown in the table 1 and FIG. 6, the content of the impurity element Feof the phosphor obtained by the chemical analysis was 400 ppm.

Comparative Example 4

As shown in the table 1, the red phosphor CaAlSiN₃:Eu was prepared underthe same condition of that of the example 8, other than using Ca₃N₂ rawmaterial having 1400 ppm content of the element Fe. The content of theelement Fe of Si₃N₄, AlN, and Eu₂O₃, which were other raw materials were20 ppm, 90 ppm, and 10 ppm, respectively.

When the phosphor powder thus obtained was irradiated with themonochromatic light of 460 nm, as shown by a thin one-dot chain line ofFIG. 5, the phosphor powder emitted red light having the emissionspectrum with a peak at 656 nm and half value width of 50 nm or more.Also, as shown in the table 1 and FIG. 6, the content of the impurityelement Fe of the phosphor obtained by the chemical analysis was 600ppm.

Comparison and Examination of the Examples 8 to 10, and the ComparativeExamples 2 to 4

It is found that from FIG. 6 and the table 1, the emission intensity isdrastically decreased when the content of the element Fe exceeds 200ppm, in the phosphor powder manufactured in the comparative examples 2to 4. This is because the element Fe has a bad influence on the emissioncharacteristics as a killer element to largely deteriorate the emissionefficiency. Such an action is considered to be caused in such a way thatwhen the content of the element Fe exceeds 200 ppm, energy transfer tothe center of the light emission of the phosphor powder is significantlyinterfered, and as a result, the emission intensity is largelydeteriorated. Accordingly, as shown in the examples 8 to 10, bycontrolling the concentration of the element Fe in the raw material tobe 200 ppm or less, the concentration of the element Fe of the phosphorpowder is suppressed to be 200 ppm or less. Under this condition, theenergy transfer to the center of the light emission of the phosphorpowder is not interfered, thereby preventing the deterioration of theemission intensity. This contributes to improving and stabilizing theemission efficiency of the phosphor.

1. A phosphor, which is given by a general composition formula expressedby MmAaBbOoNn:Z, (wherein element M is more than one kind of elementhaving bivalent valency, element A is more than one kind of elementhaving tervalent valency selected from the group consisting of Al, Ga,In, Tl, Y, Sc, P, As, Sb, and Bi, element B is more than one kind ofelement having tetravalent valency, O is oxygen, N is nitrogen, andelement Z is more than one kind of element selected from rare earthelements or transitional metal elements, satisfying m>0, a>0, b>0, o≧0,and n=2/3m+a+4/3b−2/3o), and further containing boron and/or fluorine.2. The phosphor according to claim 1, wherein a content of the boron isnot less than 0.001 wt % and not more than 3.0 wt %.
 3. The phosphoraccording to claim 1, wherein the content of the fluorine is not lessthan 0.1 wt % and not more than 3.0 wt %.
 4. The phosphor according toclaim 1, wherein the values of the m, a, b are set so as to satisfym=a=b=1, and o=0.
 5. The phosphor according to claim 1, wherein theelement M is more than one kind of element selected from the groupconsisting of Mg, Ca, Sr, Ba, and Zn, the element A is more than onekind of element selected from the group consisting of Al and Ga, theelement B is Si and/or Ge, and the element Z is more than one kind ofelement selected from the rare earth elements and the transitional metalelements.
 6. The phosphor according to claim 1, wherein the element M isCa, the element A is Al, the element B is Si, and the element Z is Eu.7. The phosphor according to claim 1, wherein the content of the elementFe is smaller than 200 ppm.
 8. The phosphor according to claim 1,wherein the phosphor is in a powdery state.
 9. The phosphor according toclaim 8, wherein an average particle size of the phosphor is not morethan 20 μm and not less than 0.1 μm.
 10. The phosphor according to claim8, wherein a specific surface area of the phosphor powder is not morethan 50 m²/g and not less than 0.1 m²/g.
 11. A manufacturing method ofthe phosphor having the structure according to claim 1, comprising:weighing and mixing a compound containing the element M, the compoundcontaining the element A, and the compound containing the element Z or asimple substance of the element Z, and a boron compound and/or afluorine compound, to obtain a mixture; firing the mixture, to obtain afired object; and pulverizing the fired object, to obtain the phosphor.12. The manufacturing method of the phosphor according to claim 11,wherein the compound containing the element M, the compound containingthe element A, the compound containing the element B, and the compoundcontaining the element Z or a simple substance of the element Z, and thecompound of 100 ppm or less content of Fe as the boron compound and/orthe fluorine compound are used.
 13. The manufacturing method of thephosphor according to claim 12, wherein a nitride of group II expressedby a general formula M₃N₂ containing 100 ppm or less of element Fe(wherein the element M is more than one kind of element selected fromthe group consisting of Mg, Ca, Sr, Ba, and Zn) is used as the compoundcontaining the element M.
 14. The manufacturing method of the phosphoraccording to claim 13, wherein the nitride of the Group II elementmanufactured by nitriding a simple substance of 2N or more containing100 ppm or less Fe is used, in a nitrogen atmosphere or in an ammoniaatmosphere at the temperature of 300° C. or more.
 15. The manufacturingmethod of the phosphor according to claim 11, wherein AlN having anaverage particle size of 0.1 μm to 5.0 μm is used as the compoundcontaining the element A, and Si₃N₄ having the average particle size of0.1 μm to 5.0 μm is used as the compound containing the element B. 16.The manufacturing method of the phosphor according to claim 11, whereinthe boron compound is BN and/or H₃BO₃.
 17. The manufacturing method ofthe phosphor according to claim 11, wherein the fluorine compound isCaF₂ and/or AlF₃.
 18. The manufacturing method of the phosphor accordingto claim 11, wherein any one of the nitrogen atmosphere, the ammoniaatmosphere, a mixed gas atmosphere of nitrogen and hydrogen, and themixed gas atmosphere of the nitrogen and ammonia is used, in the step ofobtaining a fired object by firing the mixture.
 19. The manufacturingmethod of the phosphor according to claim 11, wherein a nitrogen gas of80% or more concentration is used, as an atmosphere gas during firing,in the step of obtaining the fired object by firing the mixture.
 20. Themanufacturing method of the phosphor according to claim 11, wherein themixture is fired while ventilating the atmosphere gas at the rate of0.01 L/min or more, in the step of obtaining the fired object by firingthe mixture.
 21. The manufacturing method of the phosphor according toclaim 11, wherein the temperature is set at not less than 1200° C. andnot more than 1600° C. during firing, in the step of obtaining the firedobject by firing the mixture.
 22. The manufacturing method of thephosphor according to claim 11, wherein a pressurizing state of theatmosphere gas during firing is set at not less than 0.001 MPa and notmore than 0.1 MPa.
 23. A light source, comprising the phosphor accordingto claim 1, and a light emitting part.
 24. The light source according toclaim 23, wherein a wavelength range of light emitted from the lightemitting part is 250 nm to 550 nm.
 25. The light source according toclaim 23, wherein an LED (light emitting diode) is used as the lightemitting part.